A Two-Cohort, Open-label, Multicenter Phase II Trial Assessing the Efficacy and Safety of Pertuzumab given in Combination with Trastuzumab and Vinorelbine in First Line Patients with HER2-positive Advanced (metastatic or locally advanced) Breast Cancer

The purpose of this research study is to compare the overall response rates of pertuzumab given in combination with trastuzumab in a single infusion bag followed by vinorelbine, versus giving pertuzumab, trastuzumab and vinorelbine given in separate infusion bags. The results of this study could minimize in-clinic time and therefore make treatments more convenient for patients.